Micro CHP

Combined Heat and Power (CHP) is a low carbon technology which produces both hot water and electricity. It’s been used mostly at the commercial level for some time but there is a small domestic version, known as Micro CHP.

To date, it’s not been staggeringly successful. The proposition isn’t that appealing, at least as far as homeowners are concerned. You shell out about two or three times as much as your would for a gas boiler, and you get some of your electricity requirement thrown in with your hot water. Whilst large and medium sized CHP plants are doing rather well, down at the micro level things have come becalmed, especially as the only one commercially available, the gas-fired Whispergen, pictured here, has temporarily ceased production.

Thanks to the boys over at Carbon Limited who have flagged up a report from The Carbon Trust on the micro CHP. It has drawn some interesting conclusions in comparing the performance of 87 Micro CHP units with 27 condensing boilers over a four-year period.

• Key finding is that in order to operate effectively, micro CHP has to be in a situation where it can run for long periods uninterrupted. If the system cycles on and off frequently, it ends up using more electricity than it generates.

• Essentially this means that they are suitable for sites such as residential care homes and leisure centres, where there is a reasonably large and consistent hot water demand, In these instances, there can be significant savings — the report quotes 15% to 20% — relative to using condensing boilers

• But in housing, micro-CHP advantages are marginal at best. The demand has to be significant to make any savings, so it may be a runner if the house is very large or very old and uninsulated. Think listed manor houses – that sort of thing. The cut-off point identified by the report is a heat demand of more than 20,000kWh/annum, which would apply to almost all 20th century housing over 200m2 internal floor area (say five bedrooms).

• One of the main issues with today’s generation of micro CHP is that they only produce 1 unit of electrical power for every 10 units of hot water. This doesn’t match general domestic use, which is more like 1:3. Not until new technology kicks in (fuel cells anyone?) will a micro CHP plant start producing a better balance.

• Having said that, there is a good match time-wise. Peak electricity and hot water demand tend to occur at the same time (think dark winter nights), unlike technologies such as roof mounted PV arrays. So there is every chance that the electricity you produce, you will actually consume rather than having to export it to the grid at knockdown prices.

• The report also has some factoids about condensing boilers. It concludes that they achieve efficiencies about 5% less than their SEDBUK rating would suggest. And also that the electrical controls use large amounts of power to run the pumps, fans and control systems. Some designs are worse than others and the difference is significant. In some instances, the electrical consumption associated with condensing boilers may account for 15% of the household electricity bill.

Why George is Wrong

George Monbiot writes in today’s Guardian about the plight of the very poor in Britain and how badly they are served by our social housing. It’s a long piece, just over 1200 words, and he spends almost the whole piece exploring the plight of some desperate families, who Shelter seem to have put him in touch with.

Then suddenly, at the end of the article, without so much as an argued link, he switches into conclusion mode: I find myself, to my intense discomfort, supporting the preposterous housing target (i.e. to build 3 million new homes by 2020). There is a legitimate debate to be had about where and how these homes are built. However - though it hooks in my green guts to admit it - built they must be.

It’s a pity he didn’t spend a little longer analysing his green guts because he could, and should, have come to a very different conclusion. Britain most definitely does not need 3 million new homes in the next twelve years, especially if they are all to be one- and two-bedroom flats. Bad as the plight is of his case studies, Wendy Castle, Jacqueline Pennant and the Afghani asylum seekers Aisha and Abdul Omarzaiy, the situation is not going to be improved by a huge housebuilding programme. The flats that they live in will still be there in 2020 and the chances are that they will still be filled with either the same families or ones just like them.

Our borders are porous and however cramped the housing is in Kensington & Chelsea, it’s still a toehold in London. The bottom end of our social housing market represents a result if you come from Afghanistan.

What will happen if we build 3 million new homes? In an open Britain, they will fill up with approximately 10 million new people. And as they will mostly be flats, rather than family homes, the amount of overcrowding will continue much as before.

If we really wanted to tackle the overcrowding issue, we would do better to start replacing flats with larger houses, so that social renters had somewhere to go. Just building new homes in vast numbers is now scarcely more justifiable now than building a new runway at Heathrow.

Lifetime Homes: the 16 steps

Lifetime Homes, as a concept, has been around since 1991. The idea is to make housing usable by people of all abilities and in all phases of life, including childhood. It’s not just about the disabled!

It was developed by a group of housing experts, drawn together by the Joseph Rowntree Foundation. A few of the ideas were incorporated into Part M of the England & Wales Building Regulations in 1999, but the Lifetime Homes concept as a whole is still only widely used by Housing Associations. The Code for Sustainable Homes awards eco points for building to Lifetime Homes standard and, as it stands, the standard will have to be incorporated into all new homes by 2016. You won’t be able to score the 90% rating required to meet Level 6 of the Code without it.

There are 16 design features which combined make up the Lifetime Homes standard:

• Car parking space should be easily capable of enlargement to attain a width of 3300mm

• The distance from the car parking space to the home should be kept to a minimum and should be level or gently sloping

• The approach to all entrances should be level or gently sloping

• All entrances should be illuminated

• Communal stairs should provide easy access and where levels are reached by lift, the lift should be fully wheelchair accessible

• Doorways and hallways have to be at least 750mm wide, or at least 900mm wide when the approach is head-on

• Dining and living areas should have space for turning a wheelchair and there should be adequate circulation space for wheelchair users

• The living space should be at the level of the entrance

• If homes of two or more storeys, there should be space at entrance level which should be used as a convenient bed space

• The design of the property should incorporate a provision for a future stair lift and a suitably identified space for a through-the-floor lift from the ground to the first floor

• The design of the property should provide for a reasonable route for a potential hoist from a main bedroom to the bathroom

• There should be a WC situated at the entrance level of the property and a drainage provision enabling a shower to be fitted in the future

• Walls in the bathrooms and toilets should be capable of taking adaptations such as handrails

• The bathroom should be designed to incorporate ease of access to essential amenities such as the bath, basin and WC

• Living room windows should begin 800mm from the floor or lower and be easy to open

• Switches, sockets, ventilation and service controls should be situated between 450mm and 1200mm from the floor

Comment
Most of these features can be incorporated into most house designs fairly easily and with minimal additional cost. The ones that are likely to cause problems for designers are:

• The requirement for larger bathrooms, especially the future proofing of the downstairs loo as a potential wet room. In small houses, this is a considerable space eater

• Future-proofing a lift shaft: again this is tricky in small houses

• Wide parking spaces

Ideally, from a Lifetime Homes point of view, we would all be living in generous bungalows. However, this runs completely counter to the prevailing mood in planning which demands that we squeeze as much as possible living space into the available footprint. Indeed, another part of the Code for Sustainable Homes awards points for using the basement and/or the loftspace. It’s not difficult to build a four-storey house that conforms to Lifetime Homes standard, but arguably it goes against the spirit of what Lifetime Homes is all about, which is making the whole house accessible to the physically impaired. Box ticking 1 Common sense 0.

Eco Bollocks Award: Terminal 5

News has reached me of the fantastic efforts BAA have been making to help preserve the environment at Heathrow’s Terminal 5, due to open in March 2008. It’s taken the sustainable approach to building very seriously.

Terminal 5, which is so big that it is actually three terminals, designated 5A, 5B and 5C, will use two separate water systems, one for drinking and the other for toilet flushing and irrigation. Water for the second system will be sourced from an in-house rainwater harvesting system, topped up with a borehole supply. They hope to be able to collect and re-use 85% of the rain falling on the terminal catchment area.

In addition, all the bathrooms will have dual flush toilets, and the taps will have on-off sensors combined with aerated flow. BAA trills that it aims to reduce the demand from the public water supply by up to 70%.

Come on guys, stop trilling. It’s an airport.

Planning Permission: 1959 v 2007

Our plans for a replacement dwelling have been approved. They were submitted in the last week of July, registered with the planning department on August 7th and approved 12 weeks later. A little slower than the eight weeks which they are supposed to take, but it could be worse.

The permission comes with no less than 11 conditions.

1. The permission only lasts three years: this is now standard for all planning permissions. It used to be five years, but this was effectively reduced to three a couple of years ago.
2. They demand the right to check the materials we will be using on the roof and the walls, and also request that we ensure a privacy screen at one end of the balcony.
3. We have to produce a hard and soft landscaping scheme, with details of what is there, what will be retained (and how it will be protected) and what will be planted.
4. A requirement that all this work is carried out in the first planting season after occupation.
5. The Tree Officer is to have the say-so on which trees should be protected or replaced.
6. Especially a walnut tree in the back garden.
7. The grannexe must not be a separate dwelling
8. Visibility splays to be created along the roadway entrance
9. Turning space to be provided
10. A brick and flint wall dividing the house from the neighbour is to be retained.
11. Hours of activity are defined for the building works

None of this is unduly onerous. But a lot of it still rankles because it’s all so intrusive. Conditions 2, 3, 4, 5, 6, 10 and 11 are arguably really none of the council’s business. As owner of this property, I can and should be able to do what I want to the vegetation. The condition and indeed existence of a boundary wall is a matter to be decided between me and my neighbour. And the hours of activity on site are again issues for me to sort out with the locals.

The question is why is the council getting involved in all this stuff? The site is not listed, it’s not in a conservation area, none of the trees are subject to Tree Preservation Orders (at least they weren’t before we started), so none of the conservation buttons are hit. Yet they still cannot resist micro-managing all manner of details which they wouldn’t be at all concerned with, were we not about to replace an old house with a new one.

Back in 1959 when the existing house received its planning permission, things were very different. There were just two conditions placed upon the builders:
1. That the access should be constructed to the satisfaction of the Highway Authority.
2. That a strip of land 8ft wide should be left at the front of the site to allow for possible highway improvements in the future — a condition which seems to have vanished from the 2007 version.

The 1959 permission takes up one A4 sheet of paper. The 2007 permission fills five pages.

I don’t blame our planners for this state of affairs. They are simply responding to guidelines funnelled down to them from council and ultimately from central government. But the contrast in the conditions placed upon the planning permissions between 1959 and 2007 is quite startling. It’s hard not to conclude that today we live in a world that is far more bureaucratic, far more intrusive and with a lot less freedom.

Foundations: alternative approaches

There’s a new house going up on our road. The groundworkers have just finished the excavations: it’s on a backland plot and there are tree root issues, as there often are on backland plots. The photograph shows the state of play today, ready for a foundation pour on Monday. I was talking to the builder and they’ve been asked to go down 2.4 metres in some places, plus adding slip membranes around the trenches. He reckoned that they would be using around 100m3 of readymix, around 15 truckloads.

That is one hell of a lot of readymix for a single house, although it’s not perhaps that unusual in this day and age. The NHBC in particular is incredibly hot on using shedloads of readymix concrete to overcome ground movement problems. Foundation issues are still the largest cause of claims on NHBC policies and over the years they have become more and more wary of clay ground and, in particular, tree roots. The list of species-which-spell-trouble seems to grow ever longer with every revision of the notorious Chapter 4.2 (Building near trees) of the NHBC standards.

But consider that the house at the front of the plot (on the left of the photo) is also surrounded by trees. It’s been there since the 1880s (at a guess) and I doubt very much that it has anything much in the way of foundations — the Victorians used to just spread out the bricks at the base of the wall to make up footings. And I don’t think it’s been unduly affected by subsidence. Subsidence doesn’t really happen much in our village.

So why are we putting 100m3 of readymix into the ground under this new house? The readymix alone will cost the builder at least £6,000, not to mention muck away costs for around 100m3 of spoil. And at around 300kWh/tonne, making this much concrete will release around 9 tonnes of CO2, coincidentally the same amount as the average Briton produces each year.

Remember, it’s not the weight of the house that is the issue. 300-odd tonnes of house spread out across 50 or 60 linear metres of foundations is no great load. Compared to a 40 tonne lorry being held up by a few tyres, it’s nothing. All that concrete isn’t there to hold the house up but rather to stop it moving around: the reason the foundations go so deep is to get down to ground which doesn’t shift about through the seasons.

As I surveyed the foundation trenches of this house this morning, I couldn’t help thinking of the story of Caroline Barry’s straw bale house which was built off a base of car tyres. OK, it’s maybe a little too ethnic, a little too Glastonbury for your average builder, let alone house buyer, but there’s more than a germ of a good idea here. Rather than striving to get down to bedrock, such a house would be designed to float on the ground, with the base quietly absorbing any ground movement.

Maybe it’s idle fantasy — and feel free to explain just why —but surely there must be a more intelligent way of supporting a house than just pouring more and more concrete into the ground?

Pumping heat

Spent the weekend dispensing bon-mots and advice in Harrogate at the Homebuilding & Renovating show, one of six held throughout the UK each year. This year I have been delivering a short lecture on sustainable homebuilding and it has sparked some interesting questions and comments from the audience. However this Sunday it all got a little fiery when someone asked about the difference between air source and ground source heat pumps and whether either made sense for his building project. Rather like the output from these heat pumps, my response was just a little lukewarm.

What I specifically said was that heat pumps don’t make much sense if mains gas is available but that there should be a reasonable payback against oil. “You are doing well if you get a Coefficient of Performance of more than 3.0,” I said. I have been consistently saying this for some time now and at least one heat pump manufacturer, Kensa, seem happy to agree with me.

But up stands this man in the audience who said that heat pumps could now deliver over 6.0 — i.e. twice as much heat output for the power input. Before I could stop myself, I blurted out “That’s rubbish.” It obviously hit a nerve, because he stood up and started getting shirty with me. “What do I know about it” sort of stuff. I have no idea who he was but can only guess he was working for one of the many heat pump suppliers exhibiting at the show.

This made me go all defensive and I started quoting a couple of studies back at him that showed that heat pumps often don’t deliver what manufacturers claim. If only to prove that I do know something about it, if not exactly ranking at world expert status. This of course made matters worse and our man turns around and walks out of the seminar theatre in an act of brazen defiance.

You could have heard a pin drop. Normally, these events pass by without any rancour at all and everything is sweetness and light from start to finish. Here there was a definite feeling that someone thought I that I was being out of order and should be upbraided.

What I think this shows is that the heat pump market is maturing fast, perhaps a little too fast. By all means consider the merits of using a heat pump, but don’t get sucked in by the hype, and beware claims of extraordinary efficiencies achieved.

On zero carbon cars

There is an almighty schism in the sustainability movement. On one side are the hair shirts, insisting that salvation lies in a low impact lifestyle with much less consumption and much, much less travel. On the other are the techno-fixers who believe, or at least hope, that we can continue business much as usual and that we’ll soon sort out ways of creating energy without releasing CO2 all over the place.

Most official policy and indeed most green organisations pay lip service to both sides of the debate. Thus we should become super energy efficient AND we should start to generate renewable power. Nowhere is this more evident than in our de facto manifesto for the future of housebuilding, the Code for Sustainable Homes, where Code Levels 1 through 4 are all about conserving energy whilst Code Levels 5 and 6 call for us to create it as well.

One of the great unspokens here is that we have as yet no idea how much green power we are capable of producing. The hair shirt argument rather relies on the notion that carbon-free electricity will be in short supply and that we had better get used to conserving every joule. But it is quite conceivable that this may not be the case and that if we get our act together we could generate far more green electricity than the world could ever need. If such a scenario was to be played out, it would make many of the other sustainability arguments redundant. Or at least highly questionable.

Take planning as an example. In recent months, I have sat in on several lectures about sustainable urban design and every speaker I have listened to has been at pains to emphasize the importance of getting away from car dependency. In this respect, the USA is always held up as the prime example of how not to do it (think Los Angeles and its hundreds of miles of gridlocked freeways) and medieval Europe (especially places like Tuscany) is shown as the way to go. But it goes deeper than this. The car itself is the enemy, not just for the fact that car use burns mega amounts of carbon, but also because it destroys communities by enabling everyone to shop at out of town malls and supermarkets. This in turn pulls the rug out from under the feet of small independent stores, thus making traditional town centres unattractive. This in turn leads to people driving everywhere, which in turn, leads to problems like obesity. It’s all interconnected, and it all leads back to the car.

The problem for urbanists, who want to get us all back on our bikes and back into trains and buses, is that the car is just so damned convenient. And for most of the past fifty or sixty years, we have been building our economies around the notion of car use. It’s going to be incredibly difficult to wean us away from cars.

But think how much harder this would be if cars were to become part of the solution to climate change, rather than its main bugbear. Some of the techno-fixers can see exactly this scenario taking shape in years to come. How come?

The answer lies in the use of car batteries as an energy store. One of the main problems — in fact THE main problem — with renewable energy is that it only operates in fits and starts. On a windy day, for instance, we may conceivably draw all our energy needs — and more — from wind turbines, but that won’t get us through days without wind. Similarly, solar panels don’t work too well in the dark. What we’ve been lacking to date are credible storage methods which would be able to tide us through the times when renewables are contributing very little energy. Some have suggested that rather than building hundreds of giant batteries, or maybe pumped reservoirs, we might instead be able to use millions of small batteries which would be capable of taking and returning a charge to and from the mains. Every home would have a tray of these rechargeable batteries, acting like some huge energy internet. And, furthermore, these batteries could double as power sources for electric vehicles, which in itself would act as a considerable incentive for people to install them at home.

Say each house had maybe a dozen batteries plugged into the mains. If you wanted to go out in your car, you would take one of the batteries from the tray, drop it into your car in a special battery slot, and drive off. It might only work for an hour, so if you wanted to go further, you would have to stop at a battery garage and swap your empty battery for a full one. Not only would there be enough charge in all these batteries to keep 20-odd million electric cars on the road, but also to keep the nation lit and heated during the long hours of winter darkness, not to mention a week or two of calm, overcast weather when the big renewable power plants weren’t generating.

Science fiction? Probably, but the techno-fixers other solutions (e.g. mirrors in space, pouring iron filings into the oceans) are arguably even more implausible. By 2025, we might (just) have migrated to electric zero-carbon cars and motoring might no longer be seen as the No 1. bogeyman in the battle against climate change.

The question is what effect would this have on the great sustainable planning debates? If cars switched from being one of the main drivers behind climate change to being one of the main solutions, wouldn’t this tend to make the move towards sustainable urban settlements look just a little hollow? Would we suddenly be able to start building in the countryside again? Would out-of-town shopping centres be back of the agenda? Would the idea of eco-towns be dead in the water? Or will the obesity issue have become so all engulfing by then, that cars will still be regarded with suspicion?

Let's all go down the eco-pub

Unlike Jamie Oliver, I don’t exactly have the government hanging on my every utterance, but on Tuesday evening I did get to quiz Housing Minister Yvette Cooper about her eco-towns proposals. She had just given a twenty-minute talk, at an event organised by the Princes Foundation, on why eco-towns will be the most wonderful thing since Walt Disney first came up with the idea of theme parks. In so doing, she had hit every green button you could possibly think of so many times that they were burning hot by the end of her speech. I came away with the impression that this woman is so busy dispensing initiatives that she barely has time to sit down and think. And I am worried this might actually be true.

My question to her, put very simply, was this. Why bother? We have already been told that we are going to have to build all new homes to zero carbon standards by 2016 and we have been doing sustainable master planning for yonks, without a great deal of success, so what is the big deal about eco-towns? And why only 5,000 to 10,000 homes a time? And why out in the middle of nowhere? This being, in brief, the gist of the government’s own eco-town prospectus, published in July.

Yvette Cooper talks so fast and with such zeal that I hardly took in a word she said in reply. But I gathered that what she was on about was that

a) it needs to be at least 5,000 homes to be big enough for a secondary school and

b) they are already doing sustainable urban extensions (29 was a figure mentioned in passing) and

c) we need even more new homes so we have to find lots of new places to put them.

She did let slip that that she envisaged that, if successful, these small eco-towns would grow into big ones. To my mind, that immediately suggests that the infrastructure they initially get will rapidly prove to be obsolete. She also let us collectively know that the whole point of eco-towns was that everything in them should be eco, not just the houses. If I got her list right, it was “eco-offices, eco-schools, eco-shops and even eco-pubs.”

Now this set me thinking. What on earth would an eco-pub be like? There would of course be much more to it than triple glazing and a wind turbine on the roof. It, being a sustainable community, would have to embrace the green agenda, wouldn’t it? Would it be able to sell alcohol at all? Or would it stop you buying more than one drink? “Sorry, Madge, you’ve already exceeded your daily intake.” What about the food menu? Would it be Jamie’s pub grub? Smoking has of course already gone, but what about bad language or aggressive gestures. Just how lame would it all be?

Bear in mind that Letchworth, the world’s first new town, dating from 1907, was originally built without any pubs in order to ensure the population didn’t fritter away their time and money. On this basis, an eco-pub is therefore a contradiction in terms.

Then bugger me if the Guardian today isn’t carrying the following story on its front page: Fit towns plan to tackle childhood obesity. And bugger me if health secretary Alan Johnson isn’t being quoted at length saying he would like to ensure that the ten new eco-towns become fit towns. “Mr Johnson is leading a cross-government drive to put the eco-towns concept at the cutting edge of the fight against obesity.” The week before Johnson had gone on record as saying he thought obesity was as big a threat to us as climate change, and he is obviously keen to link the two issues.

I am left wondering if he is trying to hijack Yvette Cooper’s pet eco-town project, because the day before she didn’t mention anything at all about this so-called cross-government initiative. It’s all rather disconcerting. What’s a cub reporter to make of it all? Should I go and drown my sorrows down at the eco-pub?